Researchers from the United Kingdom studied the effect of two breathing frequencies on performance times and on several physiological parameters in front crawl swimming. The breathing frequencies were one breath every second stroke ( B2) and one breath every fourth stroke ( B4). Subjects were 10 male collegiate swimmers. Each subject swam 200 meters using each breathing frequency: once with breathing frequency B2 and once on a different day with breathing frequency B4. A paper states that the results are expressed as mean plus or minus the standard deviation. One result reported in the paper states that the immediate postexercise heart rate for subjects when using breathing frequency B2 was 161 ±13 beats per minute.

The rate of decay of a radioactive substance depends upon the amount present initially. the mass y (mg) of the radioactive substance cobalt-60 present in a sample at time t (years) is represented by the exponential equation y=50e −0.1315 t . answer the following questions in complete sentences. 1. how does the exponential equation above compare to the equation for simple interest that is compounded continuously? explain the similarities. 2. what is the initial amount of cobalt-60 in the sample? 2. how much cobalt-60 is left after 8.4 years? show your work. 3. what would be the y-intercept of the graph? what does it represent? 4. after how many years will the amount of cobalt-60 left be 6.25 mg? explain what happens to the cobalt-60 after 50 years? 5. discuss some “real-world” examples and uses of cobalt-60

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.

At a book fair, joe bought 24 books at 3 for $5 and had $2 left. how much money did he have at first?